Self-healing lens material developed to prevent self-driving car accidents

Frequent traffic accidents have raised concerns about the safety of self-driving cars. However, a potential solution has emerged in the form of a self-healing lens material that can prevent accidents caused by signal distortion. A team of researchers led by Dr. Kim Jin Chul, Park Young Il, and Jeong Ji-Eun from the Korea Research Institute of Chemical Technology (KRICT), along with Prof. Kim Hak-Rin and Prof. Cheong In Woo from Kyungpook National University (KNU), has developed this innovative material. Their findings have been published in the journal ACS Applied Materials & Interfaces.

By incorporating this self-healing optical material into the sensors of autonomous vehicles, the lifespan of the product can be extended, and future technologies capable of preventing malfunctions due to surface damage can be envisioned.

Lenses play a crucial role in collecting and dispersing light, finding applications in various optical devices we use daily, such as cameras, cell phones, and glasses. However, if the lens surface sustains scratches, the received optical signal or image can be severely distorted.

The recent surge in traffic accidents caused by recognition errors and vision system malfunctions in self-driving cars, including LiDAR sensors and image sensors, has significantly impacted confidence in their safety. The development of this self-healing material brings hope for addressing such issues and enhancing the reliability of autonomous vehicles.

Structural and functional recovery of optical components coated with developed self-healing lens materials when exposed to focused sunlight with a magnifying glass for 60 sec. Credit: Korea Research Institute of Chemical Technology (KRICT)

The joint research team from KRICT and KNU has successfully created a transparent lens material capable of eliminating scratches on the sensor surface within a minute. This remarkable feat is achieved by harnessing the power of sunlight focused through a simple tool like a magnifying glass.

Typically, self-healing properties are more pronounced in flexible materials, where molecular movement within the polymer is unrestricted. However, lenses and protective coatings are typically composed of hard materials, making it challenging to incorporate self-healing capabilities. To overcome this hurdle, the researchers combined a thiourethane structure, already utilized in lens materials, with a transparent photothermal dye. This unique combination forms a “dynamic chemical bond” within the polymers, enabling them to disassemble and recombine when exposed to sunlight.

Notably, the developed transparent organic photothermal dye exhibits selective light absorption within a specific near-infrared wavelength range (850–1050 nm). This absorption does not interfere with the visible light region (350–850 nm) used by image sensors or the near-infrared region (~1550 nm) employed by LiDAR sensors.

This groundbreaking development opens up possibilities for self-healing functionality in traditionally rigid materials, paving the way for enhanced durability and longevity in lens applications.

Recovery of optical signal in LiDAR and image sensor simulated system after self-healing of scratched surface of developed lens materials with NIR light irradiation. Credit: Korea Research Institute of Chemical Technology (KRICT)

By utilizing photothermal dyes, the developed lens material absorbs sunlight, converting its energy into thermal energy. Consequently, the surface temperature of the material rises, enabling the self-healing process. Through repeated dissociation and recombination of chemical bonds within the polythiourethane structure, surface scratches can be effectively repaired.

Remarkably, the self-healing capability of the developed lens material remains intact even when scratches intersect. It exhibits exceptional resilience, maintaining a 100% self-healing efficiency even after undergoing the process of scratching and healing at the same location multiple times, exceeding five repetitions.

Dr. Lee Young Kuk, the president of KRICT, emphasized the significance of this technology as a versatile platform. By combining an affordable high-refractive polymer material with a photothermal dye, the synthesis of self-healing lens materials becomes feasible. The potential applications extend beyond autonomous vehicle sensors to encompass areas such as glasses and cameras, indicating the broad utility and impact of this innovative technology.

Source: National Research Council of Science & Technology

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